ES2375233T3 - MIXING DEVICE FOR MIXING AT LEAST TWO FLUIDS, AND ITS USE. - Google Patents

Abstract

A mixing apparatus (100) for mixing at least two fluids, the at least two fluids comprising a liquid and a gas, the mixing apparatus (100) comprising a rotating shaft (120) around its longitudinal axis (121), a first and a second impellers (122, 124) extending radially mounted on the shaft (120) and axially spaced respectively, the first impeller (122) comprising a plurality of operable curved blades (125) to move said fluids in axial direction towards the second impeller (124), and the second impeller (124) comprising a plurality of operable curved blades (125) to move said fluids in axial direction towards the first impeller (122), characterized in that said blades (125) of each impeller are Hydrodynamic surface shovels.

Description

Mixing device for mixing at least two fluids, and their use.

The invention relates to a mixing apparatus. In particular, although not exclusively, the invention relates to an apparatus for dispensing gas in a liquid.

Many industrial processes incorporate a mixing system driven by means of an impeller, for example in processes for fermentation, hydrogenation, chlorination, oxidation and carbonylation.

Impeller driven mixing systems generally incorporate an impeller mounted on a rotating shaft. It can be said that such systems have an axial longitudinal flow that is parallel with the axis of the rotating shaft and / or a radial flow that is parallel to the radially extending blades mounted on the shaft. The impeller can thus be a radial flow impeller that projects fluid in a radial direction towards a part of a chamber in which the impeller is housed, or alternatively, the impeller can be an axial flow impeller comprising radially extending blades and that they are inclined at an angle in order to direct the flow of fluid in an axial direction. Examples of axial flow impellers include marine impellers and hydrodynamic surface impellers. Mixed flow systems are known in which the impeller causes a flow in both axial and radial directions. An example of a mixed flow impeller is the 45 ° inclined blade turbine. Such mixing systems can be used in liquid-liquid, solid-liquid, or liquid-gas reactions.

A double impeller system is known for dispensing a gas in a liquid, arranged in a vessel. Specifically, in a Kuboi document, entitled “The Power Drag by Dual Drive Systems Under Gaseous and Non-Gaseous Conditions,” Fourth European Conference on Mixing, April 27-29, 1982, describes the combination of two turbines with blades inclined 45º axially spaced, in which a first impeller is mounted below a second impeller in a common shaft. The impeller blades are oriented such that the first impeller projects liquid upwards and outwards, and the second impeller projects liquid downwards and outwards. Under gaseous conditions, a gas is introduced into the vessel, the first impeller causes the incoming gas bubble flow to divide so that some flow is driven radially outward, towards the vessel walls, and some flow it is driven axially upwards, towards the second impeller.

The effectiveness of the two impeller system under gasification conditions depends on the rotational speed of the impellers. At lower speeds it is possible that bubbles that have been projected upwards by the first impeller are not affected by the second impeller. The second impeller is not able to overcome the buoyant forces and therefore the second impeller does not take part in the dispersion of gas in the liquid. Only when the rotational speed of the second impeller is increased, the buoyancy forces are overcome. Disadvantageously, a non-uniform dispersion of the gas in the liquid is obtained. This is shown in Figure 1 of the application. In order to achieve a uniform dispersion, even more disadvantageously, the rotational speed of the second impeller has been markedly increased.

US 2004/042942 discloses a reactor system for mixing a solid granular catalyst and a liquid phase. The system comprises a core in which a basket assembly is arranged. A shaft assembly comprising upper and lower impellers and blades, is mounted in the basket assembly and is operable to impel the outward flow so that it is mixed with a granular material.

Document DE 20306404 discloses a multi-carrier arrangement designed to be operated without contact, inductively or magnetically. The arrangement comprises a shaft having a useful upper agitator and a lower useful agitator. The two agitator tools are identical but opposite, being configured to cancel the axial forces acting on the arrangement.

It is highly desirable to be trained to achieve a complete uniform dispersion in an industrial process. In industrial processes where a massive gas / liquid transfer is an essential feature, this helps controllability and increases reactor performance. In such processes, when the gas is well dispersed, there may be a reasonably uniform turbulent kinetic vortex dissipation region in the liquid between, and around, the impellers, which controls coalescence and bubble breakage. If the gas dispersion is highly non-uniform, unwanted coalescence can result in a sharp increase in the size of the bubble and, therefore, it may occur that the surface area for mass interface transfer is reduced. Advantageously, a controlled kinetic energy dissipation field results in a narrow bubble size distribution across a range of specific impeller powers.

It is an object of the present invention to provide a mixing apparatus that allows a controllable mixture of fluids or solids while simultaneously providing an effective mixing environment.

In accordance with a first aspect of the present invention, a mixing apparatus is provided for mixing at least two fluids, the at least two fluids comprising a liquid and a gas, the mixing apparatus comprising a rotating shaft about its longitudinal axis, a first and second radially extending impellers mounted on the shaft and axially spaced respectively, the first impeller comprising a plurality of operable curved blades for moving said fluids in axial direction towards the second impeller, and the second impeller comprising a plurality of curved blades operable to move said fluids in axial direction towards the first impeller, characterized in that said blades of each impeller are hydrodynamic surface blades.

Preferably, the blades of each impeller are pumping into the space between the impellers. In the case of a substantially vertical shaft, the lower impeller is therefore pumping up and the upper impeller is pumping down. Preferably, the blades of each impeller are hydrodynamic surface blades. A hydrodynamic surface shovel is the Chemineer Maxflo® W. Alternatively, Lightnin A315®, A320® or A340® can be used.

Advantageously, due to the opposite axial flows created by the first impeller and the second impeller, a region of high turbulence is observed in a central mixing zone between said impellers. High turbulence is maintained in this area, and therefore there is little variation in the turbulence energy dissipation. Consequently, there is a minimal variation in the bubble size that results in a narrow distribution of the bubble size in the central mixing zone. Advantageously, a narrow distribution of the bubble size allows the chemical process or reaction to be controlled more easily. This region provides an area where the at least two fluids come in contact to be mixed. A chemical reaction can therefore be facilitated in the central mixing zone. The fluids can be liquid-solid, liquid-liquid or liquid-gas. Preferably, the at least two fluids comprise a liquid and a gas.

It is advantageous to provide a gas / liquid mixing environment in which the bubble size is widely independent of the specific power of the impeller. In such a system, the mixing time of the liquid can be varied regardless of the bubble size.

Preferably, the first impeller and the second impeller each comprise two or more blades, more preferably three or more curved blades. More preferably, these are impellers with four curved blades. The provision of an impeller with a large number of curved blades increases the shear forces acting to break large bubbles. The small bubbles produced have an average bubble diameter smaller than those produced with a first impeller and / or a second impeller with fewer curved blades and therefore, the surface area available for a reaction to occur is increased.

Preferably, the diameter of the first impeller is the same as the diameter of the second impeller. Preferably, the diameter of the or each impeller is substantially half the diameter of the vessel on which said impeller is mounted.

Advantageously, the smaller the impeller diameter, the greater the shear force created for a given power and therefore a large number of bubbles is produced, which leads to an increase in the surface area available for a reaction to occur.

Preferably, the axial distance between the first impeller and the second impeller is a separation of at least one impeller diameter. In this configuration, the turbulence created by the opposing impellers is in equilibrium in the central mixing zone, which allows the prediction of the bubble size and therefore that the reaction control takes place.

It is preferable that the total power consumed by the impeller combination is low. Preferably, the impellers operate at a low power number, preferably substantially between 1 and 5, preferably substantially between 1 and 3, and more preferably it is 1.75. In doing so, the system consumes less energy than conventional systems that operate at power numbers of typically 3.2. The power can be measured using conventional equipment, for example with extensometers.

Preferably, when operating at a low power number, a complete uniform dispersed phase distribution is achieved. This is highly desirable and is due to the energy efficiency of hydrodynamic surface blades.

Without being limited by theory, a possible explanation regarding the effectiveness of the invention is that the use of hydrodynamic surface blades reduces blade end whirlpools and converts most of the tree's energy into flow instead of energy turbulent kinetics, helping full dispersion.

Preferably, the specific power used when the first impeller and the second impeller rotate is substantially between 50 W / m3 and 900 W / m3, more preferably, substantially between 100 W / m3 and 800 W / m3.

Preferably, when opposite double thrusters of the Maxflo type are used in the system, the preferred specific power is substantially between 50 W / m3 and 900 W / m3. Preferably, when BT-6 type impellers are used, the preferred specific power is substantially between 400 W / m3 and 3200 W / m3. At such specific powers, a narrow bubble size distribution is maintained and the reaction is controlled.

Preferably, when opposite Maxflo double impellers are used, the average arithmetic size (d10) is substantially between 250 µm and 550 µm and the mean diameter (d32) of surface volume is substantially between 400 µm and 750 m. Preferably, when operating at substantially 750 µm, the d10 is substantially between 250 µm, and 350 µm, more preferably it is substantially 296 µm, and preferably, the d32 is substantially between 400 µm and 500 µm, more preferably it is substantially 450 µm. Preferably, when operating at 991 rpm, the d10 is substantially between 300 µm and 400 µm, more preferably it is substantially 330 µm, and preferably, the d32 is substantially between 460 µm and 560 µm, and so more preferred is substantially 510 µm. Preferably, when operating at 1200 rpm, the d10 is substantially between 350 µm and 450 µm, more preferably it is substantially 394 µm, and preferably, the d32 is substantially between 450 µm and 550 µm, and more preferably it is substantially 500 µm.

Preferably, when BT-6 type impellers are used, the d10 is substantially between 250 µm and 1500 µm. In particular, when operating at substantially 251 rpm, preferably the d10 is substantially between 550 µm and 650 µm, more preferably it is 633 µm, and the d32 is preferably substantially between 800 µm and 1000 µm, more preferably It is 978 µm. Preferably, when operating at substantially 380 rpm, the d10 is preferably substantially between 800 µm and 900 µm, more preferably it is substantially 841 µm, and the d32 is substantially between 1000 µm and 1500 µm, and more preferably it is of 1345 µm. At substantially 500 rpm, the d10 is preferably substantially between 500 µm and 600 µm, and more preferably is 597 µm, and the d32 is preferably substantially between 700 µm and 800 µm, and more preferably it is substantially 721 ! m. Preferably, when operating at substantially 765 rpm, the d10 is preferably substantially between 300 µm and 550 µm, and more preferably it is substantially 378 µm, and the d32 is preferably between 400 µm and 500 µm, and more preferably it is substantially 445 µm.

In a reactor in which gas is spread in a stirred liquid medium, preferably, the spread gas rate is substantially between 0.05 and 1.0 m3 / s, substantially between 0.1 and 0.5 m3 / s, and more preferably it is substantially 0.13 m3 / s at an impeller speed preferably between 50 rpm and 1200 rpm, and more preferably between substantially 50 rpm and 200 rpm.

A key parameter used in the design of gas-liquid mixing systems is the critical dispersion rate. This is the minimum impeller speed required to ensure uniform dispersion of gas bubbles. The critical dispersion rate for achieving dispersion in an opposite double flow hydrodynamic surface system in a vessel having a diameter preferably between substantially 1 and 10 m, and more preferably between substantially 2 and 5 m, is preferably between substantially 1 and 100 rpm, preferably between substantially 5 and 50 rpm, more preferably between substantially 10 and 20 rpm, and more preferably is substantially 14 rpm.

Accordingly, according to a further aspect of the present invention, the use of a mixing apparatus according to the first aspect of the invention for mixing a fluid in the liquid phase of a chemical reaction system comprising the liquid phase is provided. Preferably, the fluid is a solid, or more preferably the fluid is a gas.

Preferably, the liquid phase comprises at least one liquid phase reagent so that it reacts with a gas introduced into the liquid phase, as well as at least one liquid phase reaction product. Preferably, the liquid phase includes a gas introduced therein. Preferably, said gas comprises one or more reagents capable of reacting with the said one or more reagents. Preferably, the liquid phase comprises a catalyst system. Preferably, the reaction system is a carbonylation reaction system such as one of those mentioned in European Patents and European Patent Applications EP-A-0055875, EP-A-0106379, EP-A0235864, EP-A- 0274795, EP-A-0499329, EP-A-0386833, EP-A-0441447, EP-A-0489472, EP-A-0282142, EP-A0227160, EP-A-0495547, EP-A-0495548, EP- A-1651587, EP-A-1565425, EP-A-1554039, EP-A-1534427, EP-A1527038, EP-A-1204476, WO2005118519 and WO2005079981.

Preferably, the reaction system is a carbonylation process comprising the carbonylation of an ethylenically unsaturated compound, with carbon monoxide in the presence of a source of hydroxyl groups, preferably methanol, and a catalyst system comprising (a) a ligand bidentate phosphine, arsine or stable, and (b) a catalytic metal chosen from a group 8, 9 or 10 metal or a compound thereof, preferably palladium. Preferably, the phosphine ligand is chosen from 1,2-bis- (di-tert-butylphosphinomethyl) benzene, 1,2-bis- (di-tert-pentylphosphomethyl) benzene, 1,2-bis- (di -ter-butylphosphinomethyl) naphthalene, 1,2-bis (diadamantilfosfinomethyl) benzene, 1,2-bis (di-3,5-dimethylatedmaphosphine-methyl) benzene, 1,2-bis (di-5-terbutylatedmaphosphomethyl) benzene, 1,2 -bis (1-adamantyl tert-butyl-phosphinomethyl) benzene, 1- (diadantilylphosphinemethyl) -2 (di-tert-butylphosphinomethyl) benzene, 1- (di-tert-butylphosphinomethyl) -2- (dicongresylphosphinomethyl) benzene, 1- ( di-terbutylphosphinomethyl) -2- (phospha-adamantyl-P-methyl) benzene, 1- (diadamantilphosphinomethyl) -2- (phospha-adamantyl-P-methyl) benzene, 1- (tert-butyladantilylphosphinomethyl) -2- (di- adamantilfosfinomethyl) benzene and 1 - [(P- (2,2,6,6-tetra-methylsphosphinano4-one) phosphinomethyl)] - 2- (phospha-adamantyl-P-methyl) benzene, in which "phospha-adamantil" is selected from 2-phospha1,3,5,7-tetramethyl-6,9,10-trioxadamentyl, 2-phospha-1,3,5-trimethyl-6,9,10 trioxadamantil, 2-phospha-1,3, 5.7tetra (tr ifluoromethyl) -6,9,10-trioxadamantil or 2-phospha-1,3,5-tri (trifluoromethyl) -6,9,10-trioxadamantil; 1,2-bis (dimethylaminomethyl) ferrocene, 1,2-bis- (diterbutylphosphinomethyl) ferrocene, 1-hydroxymethyl-2-dimethylaminomethylferrocene, 1,2-bis- (diterbutylphosphomethyl) ferrocene, 1-hydroxymethyl-2,3-bis- (dimethylaminomethyl) ferrocene, 1,2,3-tris (diterbutylphosphonomethyl) ferrocene, 1,2-bis- (dicyclohexylphosphinomethyl) ferrocene, 1,2-bis (di-iso-butylphosphinomethyl) ferrocene, 1,2-bis- (dicyclopentylphosphomethyl) ) ferrocene, 1,2-bis- (diethylphosphonomethyl) ferrocene, 1,2-bis- (diisopropylphosphinomethyl) ferrocene, 1,2-bis- (dimethylphosphomethyl) ferrocene, 1,2-bis (di- (1,3,5 , 7-tetramethyl-6,9,10-trioxa-2-phospha-adamantylmethyl) ferrocene, 1,2-bis- (dimethylaminomethyl) ferrocene-bismethyl iodide, 1,2-bis- (dihydroxymethylphosphomethyl) ferrocene, 1,2- bis (diphosphinomethyl) ferrocene, 1,2-bis-a, a- (P- (2,2,6,6-tetramethylphosphino-4-one)) dimethylferrocene, and 1,2-bis- (di-1,3 , 5,7-tetramethyl-6,9,10-trioxa-2-phospha-adamantylmethyl)) benzene; cis-1,2-bis (di-t-butylphosphinomethyl) -4,5-dimethyl cyclohexane; cis1,2-bis (di-t-butylphosphinomethyl) -5-methylcyclopentane; cis-1,2-bis (2-phosphinomethyl-1,3,5,7-tetraqmethyl-6,9,10-trioxaadamantil) -4,5-dimethylcyclohexane; cis-1,2-bis (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) 5-methylcyclopentane; cis-1,2-bis (di-adamantylphosphinomethyl) -4,5-dimethylcyclohexane; cis-1,2-bis (di-adamantylphosphinomethyl) -5-methyl cyclopentane; cis-1- (P, P-adamantyl, t-butyl phosphinomethyl) -2- (di-t-butylphosphinomethyl) -4,5-dimethylcyclohexane; cis-1 (P, P-adamantyl, t-butyl phosphinomethyl) -2- (di-t-butylphosphinomethyl) -5-methylcyclopentane; cis-1- (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (di-t-butylphosphinomethyl) -4,5-dimethylcyclohexane; cis-1- (2-phosphinomethyl-1,3-5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (di-t-butylphosphinomethyl) -5-methyl cyclopentane; cis-1- (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (diadamantilphosphinomethyl) -5-methyl cyclohexane; cis-1- (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl-2- (diadamantilphosphinomethyl) -5-methyl cyclopentane; cis-1- (2-fosgfinomethyl-1,3 , 5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (diadamantilphosphinomethyl) cyclobutane; cis-1- (di-t-butylphosphinomethyl) -2 (diadamantilfosfinomethyl) -4,5-dimethyl cyclohexane; cis-1 - (di-t-butylphosphinomethyl) -2- (diadamantilphosphinomethyl) -5-methyl cyclopentane; cis-1,2-bis (2-phospha-1,3-5-trimethyl-6,9,10-trioxatricyclo- {3.3 .1.1 [3.7]} decyl) -4,5-dimethyl cyclohexane; cis-1,2bis (2-phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -5-methyl cyclopentane; cis-1- (2-phospha-1,3,5-trimethyl6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -2- (di-t-butylphosphinomethyl ) -4,5-dimethyl cyclohexane; cis-1- (2-phospha-1,3,5-trimethyl6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -2- (di-t- butylphosphinomethyl) -5-methyl cyclopentane; cis-1- (2-phospha-1,3,5-trimethyl6,9,10-trioscatricyclo- {3.3.1.1 [3.7]} decyl) -2- (diadamantilfosfinomethyl) -4, 5-dimethyl cyclohexane; cis-1- (2-phospha-1,3,5trimethyl-6,9,10-tr ioxatricyclo {3.3.1.1 [3.7]} decyl) -2- (diadamantilphosphinomethyl) -5-methyl cyclopentane; cis-1,2-bisperfluoro (2-phospha-1,3,5,7-tetramethyl-6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) -4,5-dimethyl cyclohexane; cis-1,2-bisperfluoro (2-phospha-1,3,5,7-tetramethyl-6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) -5-methyl cyclopentane; cis-1,2-bis- (2-phospha1,3,5,7-tetra (trifluoro-methyl) -6,9,10-trioxatricyl {3.3.1.1 [3.7]} decyl) -4,5-dimethyl cyclohexane ; cis-1,2-bis- (2-phospha-1,3,5,7-tetra (trifluoro-methyl) -6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) -5-methyl cyclopentane; cis-1,2-bis (di-t-butylphosphinomethyl) cyclohexane; cis-1,2-bis (di-t-butylphosphinomethyl) cyclopentane; cis-1,2-bis (di-t-butylphosphinomethyl) cyclobutane; cis-1,2-bis (2phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) cyclohexane; cis-1,2-bis (2-phosphinomethyl-1,3,5,7-tetramethyl6,9,10-trioxa-adamantyl) cyclopentane; cis-1,2-bis (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) cyclobutane; cis-1,2-bis (di-adamantyl phosphinomethyl) cyclohexane; cis-1,2-bis (di-adamantyl phosphinomethyl) cyclopentane; cis1,2-bis (di-adamantyl phosphinomethyl) cyclobutane; cis-1- (P, P-adamantyl, t-butyl-phosphinomethyl) -2- (di-t-butylphosphinomethyl) cyclohexane; cis-1- (P, P-adamantyl, t-butyl-phosphinomethyl-2- (di-t-butylphosphinomethyl) cyclopentane; cis-1- (P, P-adamantyl, t-butyl-phosphinomethyl) -2- (di-t -butylphosphinomethyl) cyclobutane; cis-1- (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) 2- (di-t-butylphosphinomethyl) cyclohexane; cis-1- ( 2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (di-t-butylphosphinomethyl) cyclopentane; cis-1- (2-phosphinomethyl-1,3,5,7 -tetrametril-6,9,10-trioxa-adamantyl) -2- (di-t-butylphosphinomethyl) cyclobutane; cis-1- (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10- trioxa-adamantyl) -2- (diadantilylphosphinomethyl) cyclohexane; cis-1- (2-phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (diadamantilphosphinomethyl) cyclopentane; cis -1- (2phosphinomethyl-1,3,5,7-tetramethyl-6,9,10-trioxa-adamantyl) -2- (diadamantilfosfinomethyl) cyclobutane; cis-1- (di-t-butylphosphinomethyl) -2- (diadamyl phosphinomethyl) cyclohexane; cis-1- (di-t-butylphosphinomethyl-2- (diadamantilphosphinomethyl) cyclopentane; cis-1- (di-t-butylphosphinomethyl) -2- (diadamantilfosfi nomethyl) cyclobutane; cis-1,2-bis (2-phospha-1,3,5-trimethyl6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) cyclohexane; cis-1,2-bis (2-phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7] decyl) cyclopentane; cis-1,2-bis (2-phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) cyclobutane; cis-1- (2phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -2- (di-t-butylphosphinomethyl) cyclohexane; cis-1- (2-phospha-1,3,5trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7] decyl) -2- (di-t-butylphosphinomethyl) cyclopentane; cis-1- (2-phospha-1,3,5-trimethyl6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -2- (di-t-butylphosphinomethyl) cyclobutane; cis-1- (2-phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -2- (diadantilylphosphinemethyl) cyclohexane; cis-1- (2-phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7] decyl) -2- (diadamantilfosfinomethyl) cyclopentane; cis-1- (2-phospha-1,3,5-trimethyl-6,9,10-trioxatricyclo- {3.3.1.1 [3.7]} decyl) -2- (diadamantilfosfinomethyl) cyclobutane; cis-1,2-bis-perfluoro (2-phospha-1,3,5,7-tetramethyl-6,9,10-trioxatricyclo {3.3.1.1 [3.7]}-decyl) cyclohexane; cis-1,2-bis-perfluoro (2-phospha-1,3,5,7-tetramethyl-6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) cyclopentane; cis-1,2-bis-perfluoro (2-phospha-1,3,5,7-tetramethyl-6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) cyclobutane; cis-1,2-bis- (2-phospha-1,3,5,7-tetra (trifluoro-methyl) -6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) cyclohexane; cis-1,2-bis- (2-phospha-1,3,5,7-tetra (trifluoro-methyl) -6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) cyclopentane; and, cis-1,2-bis- (2-phospha-1,3,5,7-tetra (trifluoro-methyl) -6,9,10-trioxatricyclo {3.3.1.1 [3.7]} decyl) cyclobutane; (2-exo, 3-exo) -bicyclo [2.2.1] heptane-2,3-bis (di-tert-butylphosphinomethyl) and (2endo, 3-endo) –bicyclo [2.2.1] heptane-2,3 -bis (di-tert-butylphosphinomethyl).

The bubble size produced by means of the invention can be small, and therefore a large surface area is provided for mass interface transfer to take place. In addition, since the bubble size distribution is narrow with a small deviation, the carbonylation reaction can be controlled.

All features described herein may be combined with any of the above aspects, in any combination unless such combinations are mutually exclusive.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic sectional side view of a prior art mixing apparatus;

Figure 2 is a schematic sectional side view of a mixing apparatus according to the invention;

Figure 3 is a schematic sectional side view of a mixing apparatus according to the invention, in use, and

Figure 4 is an additional schematic sectional side view of a mixing apparatus according to the invention, in use.

Figure 1 shows a mixing apparatus 10 of the prior art in use, in a vessel 12 containing a liquid

14. The vessel 12 has an inlet 16 through which a gas 18 is spread in the liquid 14. The mixing apparatus 10 comprises an elongated vertical rotating shaft 20 about a longitudinal axis 21, in which it is mounted so fixes a first impeller 22 and a second impeller 24 in relation to separate. The first impeller 22 is mounted above the second impeller 24. Both the first and the second impellers 22, 24 are turbines with blades inclined at 45 °.

During use, these impellers must rotate at the same speed. The first impeller 22 causes the bubbles 26 of the incoming gas to flow both in the axial direction and in the radial direction. The axial flow component creates a moment, which, together with buoyancy, prevents the second impeller 24 from operating effectively. The moment and buoyancy are only overcome by increasing the speed of the impellers 22, 24. This increase in speed causes the complete dispersion of the gas 18 in the liquid 14 as shown in Figure 1 by the lines A. The non-uniform dispersion of the Liquid 14 in gas 18 is undesirable because the mixing process cannot be controlled.

Figure 2 shows a mixing apparatus 100 according to the present invention. The mixing apparatus 100 comprises an elongated vertical shaft 120, rotatable about a longitudinal axis 121, in which a first impeller 122 and a second impeller 124 are fixedly mounted according to a separate arrangement. Both first and second impellers 122, 124 comprise a number of blades 125 of hydrodynamic surface. Each impeller 122, 124 comprises four radially extending blades 125, fixedly mounted on the shaft 120 for a cooperative rotation about the longitudinal axis, during use. Each blade 125 of each impeller 122, 124 is a hydrodynamic surface blade arranged so that it impels the surrounding fluid axially in the direction of the other impeller. The first impeller 122 or lower is thus an upward pumping impeller, and the second impeller 124 or higher is a downward pumping impeller. Although only two blades 125 can be seen in the Figure, one skilled in the art will understand that any number of blades can be used on each of said drivers, for example 3, 4 or even 6 blades. Particularly suitable impellers, commercially available, are known as Maxflo® W, A315, A320 or A340 impellers.

The first impeller 122 is mounted on the shaft 120 so that the concave face of the blades 125 is oriented in an upward direction. The second impeller 124 is spaced along the shaft 120 and is mounted so that the concave face of the blades 125 is oriented in the downward direction. The distance between the first impeller 122 and the second impeller 124 is approximately the diameter of any of said impellers 122, 124.

Figure 3 shows the mixing apparatus 100 in a cylindrical vessel 112. A gas inlet 116 is located in the bottom wall 132 of the vessel 112, adjacent to the base 132. It will be appreciated that the vessel 112 may be of an alternative configuration. anyone, for example, can be a hopper. The mixing apparatus 100 is centrally suspended in vessel 112.

Although only one mixing device 100 is shown in Figure 3, it will be appreciated that any number of mixing devices 100 could be used in chamber 112. For example, two, three or four mixing devices 100 could be mounted in chamber 112 .

It will also be understood that any number of first and second impellers 122, 124 can be mounted on the shaft 120 while maintaining the object of the invention. For example, the arrangement 200 shown in Figure 4, in which a series of first impellers 222 and a series of second impellers 224 are mounted on the shaft 220. The shaft 220 may be provided with any number of impellers 222, 224.

An alternative configuration could comprise pairs of impellers mounted on the shaft. Each pair could comprise a first impeller and a second impeller. There could be a number of pairs of impellers in any given tree, for example two, three or four pairs. In such an arrangement, the fluid, for example a gas, can be introduced into the chamber through the base or the side wall thereof, being directed below and towards the first impeller.

The first or second impeller may be driven by separate drive means such that the rotational speed of, for example, the first impeller, may be different from the rotational speed of said other impeller.

The diameter of the first and second impellers may not necessarily be the same in any of the embodiments shown. In addition, the optimal distance between two impellers depends on the geometry of the vessel and the diameter of said impellers.

During use, as in the illustrated carbonylation reaction, vessel 112, 212 is filled with fluid 114, 214. A gas 118, 218 is then directed to vessel 112, 212 through the gas inlet 116 , 216. The shaft 120, 220 is rotated with suitable drive means (not shown), in order to cause the first impeller 122, 222 and the second impeller 124, 224 to rotate about the longitudinal axis 121, 221 of the tree 120, 220 in a liquid 114.

The gas 118, 218 enters the vessel 112, 212 in the form of large bubbles 150, 215. The rotation of the first impeller 122, 222 causes the large bubbles 150, 215 to move axially towards the blades 125, 225. Large bubbles 150, 250 impact on blades 125, 225 and break into a number of small bubbles 152, 252 in the region of high turbulent energy dissipation. The small bubbles follow the fluid flow path that is initially axial and then radial.

The second impeller 124, 224 causes the axial flow in the downward direction towards the first impeller 122, 222. Due to the opposite axial flow paths created by said impellers, a central zone 160, 260, or high dissipation zone of turbulent energy The central zone 160, 260 comprises a comparatively uniform area of high turbulent energy dissipation with a high interfacial area to allow the reaction between the reagents in the liquid 114, 214 and between reagents in the gas 118, 218. In addition, because The dissipation of turbulent energy in the central area 160, 260 is maintained without much variation, a narrow size distribution of the small bubbles occurs. This narrow size distribution allows the reactor performance to be predicted and controlled.

The mixing apparatus 100, 200 is particularly suitable for carbonylation processes.

Table 1 provides an example of resulting bubble size for a Maxflo system of opposite double impellers operating at various speeds, and at 4.2 mm / s. The bubble size was determined with the use of a typical image capture camera.

N (rpm)

750 991 1200

d10 (μm)

296 330 394

d32 (μm)

450 510 500

Table 1

A distinct advantage is that it is capable of controlling the reaction that occurs between two fluids, in particular a liquid and a gas. It is also especially favorable to be able to promote an effective and efficient mixing and a massive interface transfer between at least two fluids. When applied to industrial processes, such advantages are of high commercial value.

Claims (17)

1. A mixing apparatus (100) for mixing at least two fluids, the at least two fluids comprising a liquid and a gas, the mixing apparatus (100) comprising a rotating shaft (120) about its longitudinal axis (121) , a first and a second impeller (122, 124) extending radially mounted on the shaft (120) and axially spaced respectively, the first impeller (122) comprising a plurality of operable curved blades (125) for moving said fluids in axial direction towards the second impeller (124), and the second impeller (124) comprising a plurality of operable curved blades (125) to move said fluids in axial direction towards the first impeller (122), characterized in that said blades (125) of Each impeller are hydrodynamic surface blades. 2. A mixing apparatus as claimed in claim 1, characterized in that the blades (125) of each impeller are operable so that they pump inwards in the space between the impellers (122, 124). 3. A mixing apparatus as claimed in any one of the preceding claims, characterized in that the first impeller (122) and the second impeller (124) each comprise two or more curved blades (125). 4. A mixing apparatus as claimed in any one of the preceding claims, characterized in that the diameter of the first impeller (122) is the same as the diameter of the second impeller (124). 5. A mixing apparatus as claimed in any one of the preceding claims, characterized in that the axial distance between the first impeller (122) and the second impeller (124) is a separation of at least one impeller diameter. 6. A mixing apparatus as claimed in any one of the preceding claims, characterized in that said impellers (122, 124) are operable at a power number of 1.75. 7. A mixing apparatus as claimed in any one of the preceding claims, characterized in that the specific power used when the first impeller (122) and the second impeller (124) are operable to rotate, is comprised between 100 W / m3 and 800 W / m3. 8. A mixing apparatus as claimed in any one of the preceding claims, characterized in that when opposite Maxflo double impellers are used, the arithmetic average size (d10) is comprised between 250 μm and 550 μm and the average surface volume diameter ( d32) is between 400 μm and 750 μm. 9. A mixing apparatus as claimed in any one of the preceding claims, characterized in that when impellers of type BT-6 are used, the diameter d10 is comprised between 250 μm and 1500 μm. 10. A mixing apparatus as claimed in claim 9, characterized in that when it is operable at 765 rpm, the d10 is 378 μm, and the d32 is 445 μm. 11. A mixing apparatus as claimed in any one of the preceding claims, characterized in that the spread gas rate is between 0.05 and 1.0 m3 / s. 12. A mixing apparatus as claimed in claim 11, characterized in that the spread gas rate is 0.13 m3 / s at an impeller speed of 50 rpm at 200 rpm. 13. A mixing apparatus as claimed in any one of the preceding claims, characterized in that a critical dispersion rate in a vessel having a diameter between 2 and 5 m, is between 10 and 20 rpm. 14. A use of a mixing apparatus according to any one of the preceding claims for mixing a fluid in a liquid phase in a chemical reaction system comprising the liquid phase. 15. A use of a mixing apparatus as claimed in claim 14, characterized in that the liquid phase comprises at least one liquid phase reagent to react with a gas introduced into the liquid phase, as well as at least one reaction product Liquid phase 16. A use of a mixing apparatus as claimed in claim 14 or 15, characterized in that the liquid phase comprises a catalyst system. 17. A use of a mixing apparatus as claimed in any one of claims 14 to 16, characterized in that the reaction system is a carbonylation process comprising the carbonylation of an ethylenically unsaturated compound with carbon monoxide in the presence of a source of hydroxyl groups, and a catalyst system comprising (a) a bidentate ligand of phosphine, arsine or stibin, and (b) a catalytic metal chosen from a group 8, 9 or 10 metal, or a compound thereof .